STX-16803 Guide Chip Angle

Discussion in 'STX and STXL Series Cameras' started by Sreilly, Jun 15, 2016.

  1. Sreilly

    Sreilly Cyanogen Customer

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    I’m a bit confused about setting up the FOVi in TheSkyX for the STX-16803. I know the guider is rotated 90 degrees but when I indicate that I don’t seem to pick up the guide star I’m looking for. Should that 90 or -90. I can get a guide star and calibrate OK but when I use ACP I lose the guide star quickly. So I’m guessing the geometry of the FOVi is wrong but can’t see where. We use a 3'" rotator as well and with the square chip even plate solving doesn't give me a warm feeling the guider window is placed in the proper position.Any suggestions would be great.


    Thanks,


    Steve
     
  2. Doug

    Doug Staff Member

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    Suggestion: point it at a dense star field, take an image with the guider, and run a plate solve. That will give you the exact position and orientation of the guider field.
     
  3. Sreilly

    Sreilly Cyanogen Customer

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    In the past with other cameras such as the STL-11000 it was understood that if we had the mount parked in such a manner that the ota was pointed north and level and the counterweight shaft was pointed east and level with the wires on the camera facing up the guide chip was up so if I had a star on the chip and moved to mount south the star would rise (reflector ota) and moving the mount east moved the star east. What configuration would the STX-16803 have in this orientation? I can’t find anything that shows the guide chip and main chip in one picture and it’s getting a bit maddening as the system is at SRO on the opposite coast and the time difference makes it at least 1am before it’s dark enough there to test.


    Thanks,


    Steve
     
  4. Sreilly

    Sreilly Cyanogen Customer

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    Long delay but still working on this. Funny thing is I don’t seem to be able to get enough stars on that 340 guide chip to image link. As far as rotating the FOVi to the image, that’s done automatically when I image link but the issue is where the guide chip is placed is wrong, by at least 90 degrees. That’s what I’ve been trying to solve. It gets weird because of the square imaging chip to tell where the guide chip should be. I haven’t been able to find a picture or drawing of this camera’s chip placement anywhere. I’m lead to believe that with the cables facing up the guide chip is to the side, not above/below. But which side? Looking at the STL-11000 you have the cables up and the guide chip is centered above the main chip, no problem seeing this.


    What caused this whole discussion was the fact that when I use the stock STX-16803 geometry as configured in TheSkyX and make a FOVi using the 12.5” RC the guide chip is placed wrong. The problem then becomes finding a way to place the guide chip in its proper location. I knew this because each target I tried to set up for ACP Expert failed to image due to the guide star not being found. My process for getting the coordinates for each target was to place the target in the FOVi, rotate the guide chip in TheSkyX by clicking on the guide chip and turning it to the location of the brightest star available in the guiders path (circle). By having the guider FOVi still selected I have my display (lower right corner) show the J2000 coordinates which now is showing the center of the main imaging chip. So now I have my target in a position of the main imaging chip placed so I can use the brightest guide star and have the coordinates to use as well as the supposed guider PA. For each of these targets I wasn’t getting the guide star as expected. I’ve done this hundreds of times successfully using my ST-10XME and STL-110002M cameras all using the Pyxis rotators without issues. The only issue has been trying to do the same with the STX-16803 camera.

    Steve
     
  5. Sreilly

    Sreilly Cyanogen Customer

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  6. sixburg

    sixburg Cyanogen Customer

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    With stx16803 at Sky PA zero the guide chip is 90 degrees to the right at 3 o'clock. The stock fovi in skyx is wrong, but a correction can be found in the skyx forums.



    Sent from my iPad using Tapatalk
     
  7. Sreilly

    Sreilly Cyanogen Customer

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    Appreciate the reply but mine seems to be at 9 o'clock, 270 degrees, or 90 counter clockwise. I did a test by putting M57, east of the Meridian, dead center of the main imaging chip with a PA of 0. Then I used the Jog function in APCC and moved west, M57 moved to the left of frame and at about 48-50 arc minutes it appears at the bottom of the guide chip. an additional 2 arc minute jog and it moves up near center of the guide chip. Why this is 180 degrees different remains a mystery but I think the difference is my images are plate solved to be at a PA of 0 while maybe yours isn't?

    Steve
     
  8. Sreilly

    Sreilly Cyanogen Customer

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    Doug, I can't get near enough stars for Pinpoint or Image link to solve the guider image. I think the FOV is just too small. I even tried using PP and the USNOA2 catalog without any luck. Astrometry couldn't do it either.
     
  9. Doug

    Doug Staff Member

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    Try putting the guider on a cluster, so there are lots of stars.
     
  10. Robert Mueller

    Robert Mueller Standard User

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    Steve,
    Consider trying this. Look inside the telescope and at least with my camera I can see the opening through the baffle tube. If you can the guider prism should be visible. Then use the rotator to put the guider on the top side of the OTA.

    I then do a closed loop Slew to a bright star like Vega. Start your guider doing continuous short exposures. Once centered in the main CCD you can jog the mount in Dec/RA moving the star until it is centered in the guider Image. Make adjustments of the Sky X FOVI until it is centered over the star on your current telescope cross hair position.

    Worked good for me with self guidng filterwheel on STXL 11002.

    Hope that helps...
    Robert Mueller
     
  11. Sreilly

    Sreilly Cyanogen Customer

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    That would work if the system wasn't on the other coast. I'm in Virginia while the telescope is in California. I have a picture of the imaging system and now know that the guide chip is rotated 90 degrees counter clockwise. So now figuring out the orientation of the MMOAG is the next big question. It appears from the picture Sam sent me is that the MMOAG is on the same side as the water cooling inlet/outlet. It seems that the drawings that SBIG had posted on the previous cameras aren't posted for the new ones, or at least the STX-16803. Can anyone give an educated guess where the MMOAG is mounted versus the guide chip from the picture posted here?
     

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    Last edited: Aug 22, 2016

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